1. Field of the Invention
This invention relates generally to gas turbine engine rotors having air cooled turbine blades and, more particularly, to end seals at the turbine blade bases.
2. Description of the Prior Art
With more emphasis on fuel economy and more extensive use of air cooled turbine blades, minimizing the loss of cooling air from blade delivery circuits is an important design consideration. One very difficult area to seal is the turbine blade-turbine wheel attachment interface. Typically, cooling air is directed into clearance slots or root manifolds in the wheel inboard of the individual blade attachments from which it flows into the internal cooling cavities of the blades. The typical fir tree attachment on each blade base fits snugly into corresponding wheel lugs and under centrifugal loading seals tightly against leakage across the width of the wheel. However, due to manufacturing tolerances the lengths of the blade bases and the width of the wheel may differ from blade to blade and wheel to wheel. The result is leakage at the ends of the root manifolds between the blades or wheel and cover plates normally installed to prevent such leakage. An end seal according to this invention reduces cooling air loss usually attributable to manufacturing tolerances between blade bases and the turbine wheel.